The invention relates to a combination surgical drill guide and retractor. More particularly, the invention relates to a surgical instrument which simultaneously retracts the skin at the sides of an incision and acts as a drill guide for the surgical drilling of anatomical bone. The inventive device is particularly useful for the treatment of bone fractures in the zygomaticofrontal and infraorbital rim regions.
The treatment of bone fractures in the craniomaxillofacial region generally proceeds by reducing the fractured bones to their anatomically correct positions, and thereafter fixing the bones in place. The bones may be fixed into place either by interosseous wiring, or by the technique of miniplate osteosynthesis. Particularly in the case of zygomatic fractures, interosseous wiring may not provide stable fixation. On the other hand, miniplate osteosynthesis is capable of providing rigid internal fixation in the mid-face region, and is the clearly preferred technique in the case of zygomatic, or cheek bone fractures requiring fixation after reduction.
Miniplate osteosynthesis for mid-face fractures proceeds as follows. An incision is made in the region of the fracture, the skin is retracted, and the bones are reduced to their correct anatomical positions. A miniplate or template is then positioned onto the reduced bone structure. The miniplate contains a number of countersunk holes which are designed to receive surgical screws. While the miniplate is held in place on the reduced bone structure, a drill bit is inserted through the holes of the miniplate and the bone structure is drilled in line with the holes of the miniplate. Thereafter, the drill bit is removed and self-tapping screws are screwed through the miniplate and the bone structure. The miniplate is thereby fixed into place and holds the bone structure together so that it can heal.
It is of course apparent that in drilling the holes in the bone structure, the surgeon does not wish to drill too deeply into the orbital region. Complications, such as blindness, extraocular muscle dysfunction, retinal damage, and severe trauma could result if the depth of holes is not gauged accurately. Accordingly, it is desirable during this drilling procedure to use an instrument which will prevent the surgeon from drilling too deeply into the ocular region.
Heretofore, a special orbital drill guide has been proposed for use in performing miniplate osteosynthesis in the orbital margin. (See, e.g., FIGS. 10.4-6, appearing on page 181 of Kruger et al, Oral and Maxillofacial Traumatology, Vol. 2, Quintessence Pub. Co., Inc., Chicago (1986)). The special orbital drill guide consists of a handle, a curved C-shaped arm attached to the handle, and a plunging mechanism also attached to the handle. The plunging mechanism consists of an outer sleeve and an inner sleeve, each of which has a through-going bore. The inner sleeve is slidably mounted within the outer sleeve, whereby it functions as a plunger. Both inner and outer sleeves are mounted on the handle in line with the C-shaped member.
To employ the special orbital drill guide, an assistant uses malleable retractors to retract the sides of the incision. With the surgeon holding the drill guide by the handle, the C-shaped arm is inserted into the incision and manipulated until it is positioned on and behind the orbital bone. The tip of the C-shaped arm is thus able to act as a protective stop behind the bone to be drilled. The outer sleeve is aligned with one of the holes in the miniplate and the inner sleeve is plunged forward through the outer sleeve until it comes in contact with a hole of the miniplate. Thereafter, a drill bit is inserted through the bore of the inner sleeve and a hole is drilled through the orbital bone in line with the hole of the miniplate. The tip of the C-shaped arm prevents the drill bit from penetrating too deeply into the ocular region.
The special orbital drill guide described above, while useful, is not entirely satisfactory for the described procedure. First, the special orbital drill guide, particularly its plunging mechanism, is difficult to manipulate and keep in place when drilling bones. Second, the C-shaped arm is not very well adapted to go around the orbital bone and act as a protective stop. The arm is too narrow to act as a retractor and its hemispherical shape extends too far into the orbit creating pressure on the eyeball which can cause contusion of extraocular muscles and retinal detachment. Third, the special orbital drill guide does not include any mechanism to retract the contra-lateral side of the incision. Since one of the surgeon's hands will be needed to hold the drill guide in place and the other hand will be needed to perform the actual drilling, an assistant will be required to retract the incision.
Accordingly, it is an object of the present invention to provide a combined surgical drill guide and retractor which will simultaneously act as a drill guide for drilling anatomical bones and also retract the sides of an incision.
It is another object of the present invention to provide a combined surgical drill guide and retractor which is easily manipulable with one hand.
It is yet another object of the present invention to provide a combined surgical drill guide and retractor in which a protective stop is contoured more closely to the shape of the orbital bone in order to lessen pressure on the eyeball.